Supercharger Cooling

ABSTRACT

A supercharger cooling system provides a path for coolant from an air/coolant heat exchanger to a supercharger intercooler and then loops around the supercharger housing proximal to a hot outlet end of the supercharger and back to the heat exchanger. The heat exchanger may be a dedicated air/coolant heat exchanger or be a vehicle radiator. The intercooler is sandwiched between the supercharger and intake manifold and cools the flow of hot compressed air from the supercharger into the intake manifold. The supercharger cooling loop cools the bearings and seals, the forward ends of the male and female rotors, and the male and female rotor gears. The cooling loop is preferably located between the supercharger rotors and the rotor drive gears to form a barrier to heat. A dedicated pump cycles the coolant flow and restrictions control the flow of coolant to the supercharger.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation In Part of U.S. patentapplication Ser. No. 12/567,679 filed Sep. 25, 2009, which applicationis incorporated in its entirety herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to supercharger cooling and in particularto cooling a hotter end of a supercharger including two or more rotatingrotors.

Modern roots supercharger have improved efficiency by having an axialinlet at an inlet end and timing gears at an opposite end.Unfortunately, the opposite end is hotter than the inlet end exposingthe timing gears to such heat reduced gear and lubricant life.

Twin screw type superchargers draw air into the rear of the superchargerand compress the air as it travels from the rear to the front of thesupercharger between supercharger rotors. According to the ideal gaslaw, the air traveling through the supercharger is heated proportionalto the compression of the air inside the supercharger and is thus hotterat the front of the supercharger then at the rear of the supercharger.Further, no supercharger is 100 percent efficient, and although screwtype superchargers are more efficient than roots-type superchargers,they remain approximately 70 to 80 percent efficient, which means thatif the ideal temperature increase is 100 degrees, the actual temperatureincrease in 20 to 30 percent greater (in terms of absolute temperature).This temperature variation from the front and the rear of thesupercharger results in a corresponding unequal heating of superchargercomponents, and as a result, unequal expansion of the superchargercomponents and an accompanying variation in clearances (for example,rotors, cases, front plate, gears, bearings, and the like) betweensupercharger components. The rotor bearing are interference fit, andwhen the end cover becomes hot enough, the bearing may rotate in thebearing seats, damaging the seats, and causing the rotors to contact anddestroy the supercharger.

When the front plate expands from heat, gears positioned by the frontplate experiences an increased gear clearance. Correct gear positionsare critical in a twin screw supercharger because the gear positionsdetermine the location of the male and female rotors and theirseparation. Excessive gear clearance may also result in rotor contact,and proper operation of the supercharger requires that the rotors remainin phase with each other throughout the operating temperature range ofthe supercharger, which is between 100° F. and 450° F.

A possible solution to the variation of clearances with temperature isto increase rotor to rotor clearance to compensate for the temperaturevariation over the entire temperature range of supercharger operation.Unfortunately increasing the clearances in a twin screw typesupercharger reduces supercharger efficiency. Further, increasing gearclearance results in noisy supercharger operation which is oftenobjectionable to a driver, and accelerates wear of the gears.

Further, the rotors of twins screw type superchargers are generally madefrom aluminum. The aluminum rotors generally have 0.003 inches to 0.004inches of clearance and thus controlling the expansion of the rotors,regardless of the clearances between gears, has been an issue with thetwin screw type superchargers for decades. Greater than ideal clearanceshave been incorporated into the supercharger designed to deal with rotorexpansion. Unfortunately these large clearances reduce superchargerefficiency resulting in hotter air charges, lower output, and higherpower requirement for operating the supercharger. Further, should therotors contact each other due to excessive expansion, the superchargeris generally destroyed.

The front (output) or discharge side of the supercharger is the hottestand rotor contact always occurs towards the front of the supercharger.The rear (inlet) or intake is ingesting cooler ambient air so there isgenerally no rotor contact at the rear end of the supercharger. And, thehigher the temperatures inside the supercharger, the more severe therotor contact and the farther the contact reaches from the rear to thefront of the supercharger.

The rotors fore and aft shafts and bearings support and stabilize thepositions of the rotors. Unfortunately, the front plate having a highertemperature expands more than the rear plate which is closer to ambientair temperature. This temperature imbalance accompanied by the expansionimbalance causes the front of the rotors to separate more than the rearof the rotors. The rotor gears are attached to the front of the rotorsand as a result experienced increased gear lash as the fronts of therotors separate. Both the gear lash and the rotor expansion move therotors outward closer to the supercharger case and the timing changefrom the excess gear lash results in circumferentially excess movementof one rotor or in relation to the other.

In addition to loss of efficiency and damage to the supercharger, theincreased temperatures shorten the life of supercharger seals.

The front case of the supercharger contains the oil used to lubricatethe gears and bearings. Friction from the rotating gears, bearings, andseals heat the oil, and higher supercharger rpm, greater boost, andhigher air temperature at the front of the supercharger, furthercontribute to higher oil temperature. These effects combine to makecontrolling the temperature of the twin screw supercharger extremelydifficult.

A possible solution to cooling the supercharger is to provide apressurized flow of engine oil to the supercharger gears. Unfortunately,this approach requires external lines to provide a source of pressurizedoil to the supercharger, and external drain lines from the superchargerto the engine oil pan to drain the oil from the supercharger, whichcreate potential oil leaks. Further, additional heating of engine oilraises oil temperature and affects oil flow reducing the cooling affectof the oil.

Thus, a need remains for cooling the front (output) end of a screw typesupercharger.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providing asupercharger cooling system which provides a path for coolant from anair/coolant heat exchanger to a supercharger intercooler and then loopsaround the supercharger housing proximal to a hot outlet end of thesupercharger and back to the heat exchanger. The heat exchanger may be adedicated air/coolant heat exchanger or be a vehicle radiator. Theintercooler is sandwiched between the supercharger and intake manifoldand cools the flow of hot compressed air from the supercharger into theintake manifold. The supercharger cooling loop cools the bearings andseals, the forward ends of the male and female rotors, and the male andfemale rotor gears. The cooling loop is preferably located between thesupercharger rotors and the rotor drive gears to form a barrier to heat.A dedicated pump cycles the coolant flow and restrictions control theflow of coolant to the supercharger.

In accordance with one aspect of the invention, there is provided asystem for circulating engine coolant generally at 160 degreesFahrenheit to 200 degrees Fahrenheit to the hot front (outlet end) ofthe supercharger. The cooling provided reduces the temperatures of therotor bearings, seals, and gears. Providing the coolant flow to theoutlet end wall of the supercharger provides a barrier to heat therebyimproving performance and reduces wear and failures.

In accordance with another aspect of the invention, there is provided asystem for circulating engine coolant through the outlet end wall of thesupercharger. The outlet end wall includes seats for the outlet endrotor bearings and separates the rotor drive gears from the hotcompressed air in the outlet end of the supercharger. Preventingoverheating of the outlet end wall maintains proper rotor centerdistancethereby improving performance and reduces wear and failures.

In accordance with yet another aspect of the invention, there isprovided the a system for circulating engine coolant through the outletend wall of the supercharger. The outlet end wall separates the outletend wall from the hot compressed air in the outlet end of thesupercharger. Cooling the outlet end wall provides a barrier to heatreaching the rotor drive gears and lubricating oil inside the dischargeside cover which lubricates the rotor drive gears. Such cooling improveslubrication and extends the life of the lubricating oil.

In accordance with still another aspect of the invention, there isprovided the a system for circulating engine coolant through asupercharger housing proximal to the outlet end wall of thesupercharger. Cooling the housing proximal to the outlet end wallprovides a barrier to heat reaching the rotor drive gears andlubricating oil inside the discharge side cover which lubricates therotor drive gears. Such cooling improves lubrication and extends thelife of the lubricating oil.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1A is a side view of a supercharged engine according to the presentinvention.

FIG. 1B is a top view of the supercharged engine according to thepresent invention.

FIG. 1C is a front view of the supercharged engine according to thepresent invention.

FIG. 2A is a side view of a supercharger, intercooler, and intakemanifold according to the present invention.

FIG. 2B is a top view of the supercharger, intercooler, and intakemanifold according to the present invention.

FIG. 3 is a cross-sectional view of the supercharger, intercooler, andintake manifold according to the present invention taken along line 3-3of FIG. 2B.

FIG. 4 shows the supercharged engine, a heat exchanger, and coolantlines according to the present invention.

FIG. 5 is a front view of a supercharger outlet end wall and intercoolercoolant flow according to the present invention.

FIG. 6 is a cross-sectional view of the supercharger outlet end walltaken along line 6-6 of FIG. 5.

FIG. 7A is a front view of a coolant channel cover according to thepresent invention.

FIG. 7B is an edge view of the coolant channel cover according to thepresent invention.

FIG. 8 shows the supercharged engine, a heat exchanger, and coolantlines according to the present invention.

FIG. 9 shows a cutaway view of the supercharger housing proximal to theoutlet end wall showing a coolant path according to the presentinvention.

FIG. 10 shows a cross-sectional view of the supercharger housingproximal to the outlet end wall taken along line 10-10 of FIG. 9 showinga coolant path according to the present invention.

FIG. 11 shows a cross-sectional view of a single piece superchargerhousing and outlet end wall proximal to the outlet end wall taken alongline 6-6 of FIG. 5 showing a coolant path according to the presentinvention.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing one ormore preferred embodiments of the invention. The scope of the inventionshould be determined with reference to the claims.

A side view of a supercharged engine 10 according to the presentinvention is shown in FIG. 1A and a top view of the supercharged engine10 is shown in FIG. 1B. The supercharged engine 10 includes a screwcompressor type supercharger 12 attached to an intake manifold 20through an intercooler 22. The screw compressor type supercharger 12compresses air received through a throttle body 16 and provides thecompressed air to the supercharged engine 10 through the intercooler 22and intake manifold 20. The screw compressor type supercharger 12 isdriven by a belt 14 connecting a crankshaft pulley to a superchargerpulley.

A side view of the screw compressor type supercharger 12 according tothe present invention is shown in FIG. 2A and a top view of the screwcompressor type supercharger 12 is shown in FIG. 2B. A superchargerpulley 18 is attached to the screw compressor type supercharger 12 at afront (outlet) end 12 a of the supercharger and the throttle body 16 isattached at a rearward end 12 b. While the supercharger is shown ashaving the outlet end to the front, belt drives may also be provided toposition the inlet end of the supercharger to the front and thesupercharger driven from the rear, and such variations are intended tocome within the scope of the present invention. The superchargerincludes a housing 13 having a length L, an inlet end wall 51 behind thehousing 13, and the outlet end wall 47 ahead of the housing 13.

A cross-sectional view of the screw compressor type supercharger 12taken along line 3-3 of FIG. 2B is shown in FIG. 3. A first rotor 24 anda second rotor 26 are rotatably housed in a housing 13 of the screwcompressor type supercharger 12. The rotors 24 and 26 are turned by thepulley 18 and draw ambient air 28 through the throttle body 16 andthrough the rear (inlet) end 12 b and into the screw compressor typesupercharger 12. The ambient air is compressed as it passes through thescrew compressor type supercharger 12 by the rotors 24 and 26. Thecompressed air 29 is pumped through compressed air passage 30 andthrough the intercooler 22 and the intake manifold 20 into the engine10.

The power produced by a supercharging internal combustion engine 10 isgenerally increased by increasing the supercharger 12 boost pressure.Increasing the boost pressure necessarily results in increasedtemperature of the compressed air 29 being pumped into the engine 10.Such temperature increase is proportional to the absolute pressureincrease (the Ideal Gas Law) and further increased by less than 100percent supercharger efficiency. The hot air flowing through thesupercharger further heats mechanical components and lubrication oil ofthe supercharger. The air flow is heated as it passes from the inlet end12 b to the outlet end 12 a, and as a result, the components near thefront 12 a of the supercharger 12 experience significantly greatertemperature rise than near the rear 12 b. Such heating of elements nearthe front 12 a of the supercharger 12 has resulted in reducedperformance, wear to components, and mechanical failures.

The supercharged engine 12, a heat exchanger 45, and coolant lines 40 a,40 b, and 40 c according to the present invention are shown in FIG. 4.Increased pressure (i.e., boost) often requires intercooling to preventdetonation. The air to liquid coolant intercooler 22 is popular for manyinstallations because of the compact size and the elimination of acooling air flow through the intercooler required by air to airintercoolers. The intercooler 22 is conveniently mounted between thesupercharger 12 and the intake manifold 20. The circulating liquidcoolant is cooled by air 43 in a radiator 45 which is generally mountedin the front of the car. The line 40 a carries the coolant 41 from aheat exchanger coolant outlet 45 b on the heat exchanger 45 to anintercooler coolant inlet 22 a on the intercooler 22 through a pump 44.The line 40 b carries the coolant 41 from an intercooler coolant outlet22 b on the intercooler 22 to a supercharger coolant inlet 12 a on thesupercharger 12. The line 40 c carries the coolant 41 from asupercharger coolant outlet 12 b on the supercharger 12 back to a heatexchanger coolant inlet 45 a on the heat exchanger 45 to complete thecycle.

The pump 44 may be a mechanical pump or an electric pump. When anelectric pump is used the pump may be controlled, for example using apulse width modulated power signal, to provide the required coolant flow41 to the supercharger 12.

Two restricted flows 41 a and 41 b connect the line 40 b to the line 40c. The restricted flow 41 a passed through a fixed restriction 48 andthe flow 41 b passes through a variable restriction 49 to control theamount of coolant 41 flowing through the supercharger 12. The variablerestriction 49 may be thermostatically controlled and is preferablycontrolled based on supercharger 12 temperature.

A front view of a supercharger outlet end wall 47 and coolant flow 41according to the present invention is shown in FIG. 5 and across-sectional view of the supercharger outlet end wall 47 anddischarge end cover 59 taken along line 6-6 of FIG. 5 is shown in FIG.6. As the boost is increased, the temperature of the compressed air 30pumped into the engine 10 also increases, particularly at the outlet end12 a of the supercharger (see FIG. 2A). The outlet end wall 47 is incontact with the hot compressed air 30 causing the temperature of theoutlet end wall 47, the bearings 52 and 53, the shaft seals 54 and 55,the rotor drive gears 50 a and 50 b, and lubricating oil inside thedischarge end cover 59 to increase under high boost, reducingperformance and increases wear and failures.

The outlet end wall 47 is generally made of aluminium and includes seats52 a and 53 a for the bearings 52 and 53. Because of the high thermalexpansion of aluminum, outlet end wall 47 does not maintain thecenterdistance of the gears 50 a and 50 b and the rotors 24 and 26 whenthe hot compressed air 30 heats the outlet end wall 47 to high operatingtemperatures. The gears 50 a and 50 b are made of steel having acoefficient of thermal expansion different from the outlet end wall 47and as a result the gear mesh of the gears 50 a and 50 b is affected bythe expansion of the outlet end wall 47. The supercharger inlet end wallis also made of aluminium but is continuously cooled by the inlet air 28at ambient temperature, and as a result, the outlet ends 24 a and 26 aof the rotors 24 and 26 do not maintain the same rotor centerdistance asthe inlet ends. Heat is also generated by the rotor drive gears 50 a and50 b, the pulley 18, the bearings 52 and 53 and the seals 54 and 55.

Some of the heat is further transferred to oil in the space 57 betweenthe discharge end cover 59 and the outlet end wall 47. The oil iscontinuously thrown against neighbouring walls, and additionally, anumber of mounting bosses spaced around the interior of the dischargeend cover 59 tend to collect the oil in the top half of the dischargeend cover 59 delaying the oil from running down into the oil sump,resulting in the hot oil heating the discharge end cover 59. Thelubricating quality of the oil may be reduced when the oil is heatedexcessively resulting in wear to the gears 50 a and 50 b.

The supercharger cooling system according to the present invention coolsthe outlet end wall 47 thereby effectively cooling the bearing seats 52a and 53 a, the bearings 52 and 53, and the seals 54 and 55, andcreating a barrier to heat from the hot compressed air 30 reaching thegears 50 a and 50 b. As a result, the rotor centerdistance in the outletend 12 a remains very close to the rotor centerdistance in the inlet end12 b, and proper gear mesh is maintained, thereby improving performanceand reducing wear and failures. Additionally, reducing expansion allowsthe rotor to rotor centerdistance to be kept small for optimumperformance and safe operation.

More preferably, the flow 41 through the liquid coolant channel 46circles around the outside radii of the seats 52 a and 53 a of the twobearings 52 and 53 to cool the seats 52 a and 53 a, the bearings 52 and53, and the outlet end wall 47. Cooling the outlet end wall 47contributes to maintaining the centerdistance between the rotors and thegears, even under high boost conditions. Cooling the bearing seats 52 aand 53 a also helps to maintain an interference fit of the bearings 52and 53 to the bearing seats 52 a and 53 a. Cooling the outlet end wall47 also provides a barrier to heat flowing from the hot compressed airflow 30 through the outlet end wall 47 and into the space 57 inside thedischarge end cover 59, thereby preventing or reducing heating of thegears 50 a and 50 b and the oil residing in the space 57.

A front view of a coolant channel cover 56 is shown in FIG. 7A and anedge view of the coolant channel cover 56 is shown in FIG. 7B. Thecoolant channel cover 56 includes an O-ring 56 a circling it's outsideedge for sealing outside the coolant flow 41 against a recess edge ofthe outlet end wall 47. O-rings 46 a (see FIG. 6) provide a second sealbetween the outlet end wall 47 and the coolant channel cover 56 forsealing inside the coolant flow 41.

The present invention reduces heating of the discharge end cover 59because a rear face of the cooling channel cover 56 is directly cooledby the liquid coolant 41 in channel 46. The oil in the space 57 isexposed to a front face of the cooling channel cover 56 and is cooled asthe oil runs down the front face of the cooling channel cover 56.

A supercharged engine 10′, the heat exchanger 24, and coolant lines areshown in FIG. 8. The supercharged engine 10′ is similar to thesupercharged engine 10 but does not include an intercooler. The heatexchanger coolant outlet 45 b is connected to the supercharger coolantinlet 12 a.

In another embodiment, a liquid coolant channel between forward edges24′ and 26′ of the rotors 24 and 26 respectively and the bearings 52 and53 creates a barrier to heat from the hot compressed air 30 reaching thegears 50 a and 50 b improving performance and reducing wear andfailures. A cutaway view of a second supercharger housing 13 a proximalto the outlet end wall 47 showing a coolant path 60 through the housing13 a is shown in FIG. 9 and a cross-sectional view of the superchargerhousing 13 a proximal to the outlet end wall 47 taken along line 10-10of FIG. 9 showing the coolant path 60 is shown in FIG. 10. The rotorsinclude rotor shaft 24′ and 26′ connecting the rotors to the gears 50 aand 50 b and the coolant path 60 circles the rotor shafts. The coolantpath 60 is centered a distance D from the outlet end wall 47. Thedistance D is preferably less than three inches and more preferably lessthan two inches.

A cross-sectional view of a single piece supercharger housing and outletend wall 13′ taken along line 6-6 of FIG. 5 showing the coolant channel46 is shown in FIG. 11. The single piece supercharger housing and outletend wall 13′ is a single piece, and is otherwise similar to thesupercharger housing and the outlet end wall 47.

Space in the engine compartment is often limited and an embodiment ofthe supercharger cooling system according to the present inventiondescribed below uses an existing engine cooling system to provide thedesired cooling without adding significant additional parts. Theexisting engine cooling system includes a radiator mounted in the frontof the car and a water pump. The water pump circulates the existingliquid coolant through the radiator and the engine. The water pump mayalso be used to circulate a part of the total coolant flow to thecooling channel 46 in the outlet end wall 47 to cool the supercharger. Aparallel circuit comprising the lines 40 a, and 40 c is connected to theexisting vehicle cooling system with the line 40 a connected to a higherpressure point and the line 40 c to a lower pressure point. The amountof liquid coolant cycled through the cooling channel 46 is controlled bythe two restrictions 48 and 49. By altering the size of the tworestrictions 8 and 9 each flow can be determined for optimum coolingperformance.

While the above description focuses on a screw type supercharger, thoseskilled in the art will recognize that the present invention is equallyapplicable to a roots type supercharger and such cooling for a rootstype supercharger is intended to come within the scope of the presentinvention.

The liquid coolant is often a water based coolant but may also be aPropylene glycol coolant or any other liquid coolant.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

I claim:
 1. An engine including a supercharger having an outlet endcooling system comprising: an engine intake manifold providing a flow ofcompressed air into the engine; a supercharger in fluid communicationwith the engine intake manifold providing the flow of compressed airinto the intake manifold; an inlet end of the supercharger receivingambient air; an outlet end of the supercharger opposite the inlet end ofthe supercharger; a path for the ambient air from the inlet end of thesupercharger to the outlet end of the supercharger with increasingpressure and temperature as the ambient air is compressed along the pathto produce the flow of compressed air; a coolant to air heat exchangerfor cooling a coolant flow; a supercharger coolant inlet in fluidcommunication with the coolant to air heat exchanger to receive thecooled coolant flow; a supercharger coolant path residing proximal tothe outlet end of the supercharger, no portion of the superchargercoolant path greater than three inches from an outlet end wall portionof the supercharger, the supercharger coolant path in fluidcommunication with the supercharger coolant inlet to receive the cooledcoolant flow; a supercharger coolant outlet in fluid communication withthe supercharger coolant path to receive the coolant flow from thesupercharger coolant path; and the supercharger coolant outlet in fluidcommunication with the coolant to air heat exchanger to return thecoolant flow to the coolant to air heat exchanger.
 2. The engine ofclaim 1, wherein the supercharger coolant path is in a superchargerhousing of the supercharger.
 3. The engine of claim 2, wherein thesupercharger coolant path is less than three inches from the outlet endwall of the supercharger.
 4. The engine of claim 3, wherein thesupercharger coolant path is less than two inches from the outlet endwall of the supercharger.
 5. The engine of claim 1, wherein thesupercharger coolant path is between forward edges of the rotors andbearings in the outlet end of the supercharger.
 6. The engine of claim2, wherein the supercharger coolant flow resided between the rotors andthe gears and provides a barrier to heat flowing to the gears.
 7. Theengine of claim 1, wherein the heat exchanger is a vehicle radiator. 8.The engine of claim 7, wherein the coolant is pumped by a vehicle waterpump.
 9. The engine of claim 1, wherein a bypass connects thesupercharger coolant inlet to the supercharger coolant outlet bypassingthe supercharger coolant path to reduce supercharger cooling.
 10. Theengine of claim 1, wherein a first fixed bypass connects thesupercharger coolant inlet to the supercharger coolant outlet bypassingthe supercharger coolant path to reduce supercharger cooling and asecond variable bypass connected the supercharger coolant inlet to thesupercharger coolant outlet bypassing the supercharger coolant path toreduce supercharger cooling.
 11. The engine of claim 10, wherein thesecond variable bypass is thermostatically controlled to control thesupercharger cooling.
 12. The engine of claim 1, wherein: a dischargeend cover resides at the outlet end of the supercharger; and thesupercharger coolant path resides between outlet ends of superchargerrotors and the discharge end cover.
 13. The engine of claim 1, wherein:a supercharger pulley resides at the outlet end of the supercharger; andthe supercharger coolant path resides between the supercharger rotorsand the supercharger pulley.
 14. The engine of claim 1, wherein: rotorshafts connect the rotors to rotor gears driving the rotors; and thesupercharger coolant path circles the rotor shafts.
 15. The engine ofclaim 1, wherein the supercharger is a screw type supercharger.
 16. Theengine of claim 1, wherein the supercharger is a roots typesupercharger.
 17. An engine including a screw type supercharger havingan outlet end cooling system comprising: an engine intake manifoldproviding a flow of compressed air into the engine; an intercooler influid communication with the engine intake manifold providing the flowof compressed air into the intake manifold; a screw type supercharger influid communication with the intercooler providing the flow ofcompressed air into the intercooler; a supercharger housing containingscrews of the screw type supercharger; an inlet end of the screw typesupercharger receiving ambient air; an outlet end of the screw typesupercharger opposite the inlet end of the screw type supercharger; anoutlet end wall attached to the supercharger housing at the outlet endof the supercharger; rotor bearings supported by the outlet end wall; apath for the ambient air from the inlet end of the screw typesupercharger to the outlet end of the screw type supercharger withincreasing pressure and temperature as the ambient air is compressedalong the path to produce the flow of compressed air; a coolant to airheat exchanger for cooling a flow of coolant and having a heat exchangercoolant inlet and a heat exchanger coolant outlet; a first coolant lineconnecting the heat exchanger coolant outlet and an intercooler coolantinlet; an intercooler coolant path circulating the coolant fromintercooler coolant inlet to an intercooler coolant outlet; a secondcoolant line connecting the intercooler coolant outlet to a superchargercoolant inlet; a supercharger coolant path through the superchargerhousing, the coolant path less than three inches from the outlet endwall, the supercharger coolant path receiving the coolant flow from thesupercharger coolant inlet; a supercharger coolant outlet receiving thecoolant flow from the supercharger coolant path; and a third coolantline connecting the supercharger coolant outlet to the heat exchangercoolant inlet.
 18. An engine including a screw type supercharger havingan outlet end cooling system comprising: an engine intake manifoldproviding a flow of compressed air into the engine; an intercooler influid communication with the engine intake manifold providing the flowof compressed air into the intake manifold; a screw type supercharger influid communication with the intercooler providing the flow ofcompressed air into the intercooler; a supercharger housing of the screwtype supercharger enclosing rotors of the screw type supercharger; aninlet end of the screw type supercharger receiving ambient air; anoutlet end of the screw type supercharger opposite the inlet end of thescrew type supercharger; an outlet end wall at the outlet end of thesupercharger, the outlet end wall separating supercharger rotors fromsupercharger rotor gears; rotor bearings supported by the outlet endwall; a path for the ambient air from the inlet end of the screw typesupercharger to the outlet end of the screw type supercharger withincreasing pressure and temperature as the ambient air is compressedalong the path to produce the flow of compressed air; a coolant to airheat exchanger for cooling a flow of coolant and having a heat exchangercoolant inlet and a heat exchanger coolant outlet; a first coolant lineconnecting the heat exchanger coolant outlet and an intercooler coolantinlet; an intercooler coolant path circulating the coolant fromintercooler coolant inlet to an intercooler coolant outlet; a secondcoolant line connecting the intercooler coolant outlet to a superchargercoolant inlet; a supercharger coolant path between forward edges of therotors and the rotor bearings, the supercharger coolant path receivingthe coolant flow from the supercharger coolant inlet; a superchargercoolant outlet receiving the coolant flow from the supercharger coolantpath; and a third coolant line connecting the supercharger coolantoutlet to the heat exchanger coolant inlet.